Upstairs Downstairs
by KrissaBelle7
Summary: "Castle and his family had been very welcoming towards Kate, but she really needed to find a permanent solution to her housing problem. One that didn't involve the possibility of walking into a boxer-clad Castle in his kitchen at four in the morning." Post Boom! Fic for Lou's birthday.
1. Chapter 1

A/N: Happy Birthday Lou! Thank you for all the wonderful things you bring into the Castle fandom, we are eternally lucky to have you as our Prompt Overlord.

Beta by Katherine. She wades through my mess so you guys get to read stories ;)

Disclaimer: not mine.

* * *

Kate Beckett stared at the blindfold in her hand and then back to her best friend. Lanie merely arched an eyebrow at her and crossed her arms. Sighing, Kate started putting the blindfold over her eyes.

"Lanie, is this really necessary?" she asked, adjusting the band of cloth so that it sat comfortably over her eyes.

"I swear girl, you'll be thanking me. I've found you the most amazing apartment in Manhattan, and if I didn't still have two years on my lease, I'd snatch that place already. It's that good. Trust me, Kate, it's worth the surprise."

Kate rolled her eyes at Lanie's dramatics, not that the gesture could be seen thanks to the blindfold anyway, and leaned back into her seat.

Kate wrinkled her nose at the myriad New York taxi cab smells she was being subjected to as they made their way across town to meet a real estate agent Lanie had found for Kate. It had taken her a few days to sort out her life after her apartment exploded, but now that she's had the time, Kate had been actively apartment hunting.

It wasn't that Castle's loft was awful, she just didn't want to overstay her welcome. Castle and his family had been very welcoming towards Kate, but she really needed to find a permanent solution to her housing problem. One that didn't involve the possibility of walking into a boxer-clad Castle in his kitchen at four in the morning.

She had met Lanie for lunch, and when they were done, the medical examiner had ushered her into a taxi, passing a piece of paper with the address of their destination to the driver before fishing inside her bag for a blindfold.

Their journey didn't take long, which led Kate to suspect they were still either in Tribeca or Greenwich Village. "Just to be clear, you do realize that I have a budget, right?" Kate asked.

Lanie didn't reply, merely nudging her out of the taxi. Kate heard pedestrians walking about her, so she did her best not to fidget around despite the nervous excitement bubbling in her stomach. Instead, Kate tried to pick up on the snippets of conversations floating pass for clues to their location. Some teenagers walked by slowly, chattering about a movie; a rushed businessman on his phone, in and out of earshot within seconds. Then she felt Lanie's hand on her arm, guiding her, presumably, across a sidewalk.

Kate noticed the transition from sidewalk to indoors immediately as cool air blew through her hair. A sense of déjà vu washed over her but Lanie was quick to guide her to the elevator.

Kate swore the elevator car smelled faintly of Castle's aftershave, but she'd never admit that thought to Lanie. Instead she asked, "Uh, Lanie, you're not… taking me home, are you?"

"Home?" Lanie's teasing voice came from her right side. "I didn't realize writer boy's place is now considered _home_."

"Oh shut up, you know what I mean," Kate muttered, frowning at her slip up.

"No, I am not taking you _home_ to writer boy's loft."

The elevator dinged, signaling their arrival and Lanie guided Kate out. "Hello Eric," Lanie greeted, as Kate stood beside her friend, her lips quirked in an awkward smile. Lanie quickly introduced Kate to the real estate agent, explaining, "Don't mind the blindfold, I just want to surprise her with the interior of the place."

Kate heard the door unlock and finally headed inside with Lanie's hand on her elbow. " _Now_ are we done with the cloak and dagger theatrics?" she asked, already reaching for the blindfold.

"Alright, take it off."

Kate pulled the blindfold off with one hand, the other immediately reaching to comb through her mussed up hair. A quick look across the space had Kate slowing down her movements. This place was…

This place was amazing.

She exchanged a proper handshake with Eric, and began walking around the apartment as Lanie grinned happily by the closed door.

She had to hand it to Lanie, this place was a huge step up from the previous apartments she'd visited.

There were huge panels of windows across the room with the curtains pulled over, but Kate suspected the natural lighting could do wonders for the room. She wandered into the first room on her right, finding a decent sized bedroom, then checked out the bathroom and kitchen, falling more and more in love with the place with each step.

Eric and Lanie were waiting for her in the living room. "Which part of town are we at?" Kate asked, heading for the windows. Her fingers were itching to pull open the curtains.

"Soho," Eric replied.

That stopped Kate short.

 _Soho?!_

"Does this place have rent control or rent stabilization? How long is the lease?" Kate asked as she turned to lean against the window and felt the warmth from the sun slowly seep through her back.

Eric was quick to give her the details, and Kate was surprised to find the place was within the upper ranges of her budget. "Is the place haunted? Did someone die here?" Kate speculated, looking from Eric to Lanie, "Or does a rock star live in the unit above and play loud music in the middle of the night? No offense, but what's the catch? A place like this, in Soho, with that price? Something isn't adding up."

Kate glanced at the walls but didn't see any watermarks. Maybe it was the view or location of the building itself? She turned to reach for the curtains once more but Eric chuckled and answered her earlier questions, stopping her movements. "No ghosts or sound complaints, the previous owners moved upstate because the wife was diagnosed with some respiratory problems, so they decided to move out of the city. Lanie is a friend of a friend, so I promised to let you see the place before showing it to other potential tenants."

Kate nodded slowly, still looking around the spacious apartment. Eric continued, "It's a secure building with 24-hour doorman service, a side entrance accessible only to residents, one parking unit in the basement but you can apply for more at your own cost, two sets of elevators, and the building even has it's own back up generator."

"C'mon, Kate, you know you love the place. And this is why I'm the best best friend in the whole world," Lanie said, nudging her friend and earning a smile in return.

"Alright Lanie, I'll give that to you," Kate said, finally pulling the curtains open to flood the place with light. "You're the…" Her words dried up in her mouth.

She recognized this view. She's only been seeing it daily for the past week.

 _From Castle's loft._

"Lanie Parish, you are so dead."

* * *

Prompt: post Boom, Kate finds the perfect apartment. It's spacious, light, affordable, and in a secure building. Only problem is, it's directly downstairs from Castle's loft.

A/N: There are six chapters in total, I'll be posting a new chapter every day :)


	2. Chapter 2

A/N: Beta by Katherine. Mistakes are still mine though.

Disclaimer: not mine

* * *

Three days later, Lanie showed up at the loft to help Kate move into her new place. Castle greeted her at the door with a disarming smile. "Lanie, good to see you. Come on in. Kate's just gone to put something away, she'll be down shortly."

Castle ushered Lanie to the kitchen and was offering to fix her a drink when Kate showed up.

"Castle, you're not charming the location of my new place out of Lanie, stop trying." Kate then turned her attention to her friend, greeting Lanie warmly as Castle flushed a light shade of pink.

"Can't believe you still haven't told Writer Boy you're living-"

"That's enough now. You're here to help me _move_ ," Kate warned Lanie, glaring daggers at her friend.

"I'm more than happy to help you move," Castle volunteered, no doubt still angling for a way to learn of her new address.

"Lanie volunteered," Kate told him sweetly. Too sweetly. Kate sensed the wheels turning in his head, so she continued before he had a chance to formulate his questions.

"Anyway, we need to go. Thank you for uhh, well, everything," Kate finished lamely. She tried not to read too much into the flash of disappointment in Castle's eyes, focusing instead on watching Lanie in her peripheral vision as she moved away to Kate's bags by the front door.

Castle took a step closer to Kate, forcing an easy smile on his face. "Well, Casa Castle hopes you enjoyed your stay here, and we look forward to your next visit."

Kate couldn't help but mimic his smile. She reached up to tuck a strand of hair behind her ear, stalling for time. "I'm sure you can't wait to get me out of your hair. I just wanted to tell you…" Kate made the mistake of looking up into his expectant face, and the speech she had been rehearsing in her head for the past two nights just vanished.

"I... I mean," she stuttered, feeling more flustered by the second. "I really… Thank you," she forced out, sticking her arm out. "It really means a lot to me." Castle shook her proffered hand as Kate mentally kicked herself.

They broke off the handshake looking more like awkward acquaintances, almost bumping into each other in their haste to make it over to the front door.

Castle insisted on carrying the two small duffel bags to the lobby despite Kate's insistent protests that it wasn't necessary. Lanie wasn't any help at all, grinning at her two friends, looking way too satisfied with herself.

He stayed on and even hailed a cab, helping the two women in, lingering in an obvious attempt to catch Kate's address. Kate steeled herself and shut the door firmly, trying her hardest not to notice how forlorn Castle looked on the sidewalk as the taxi pulled away.

"Where to, miss?"

"Uh, just down the road and then circle around the block."

The cabbie began to protest, but Kate shut him up, telling him, "My friend here will pay double the fare." He grumbled to himself, but continued driving.

Kate leaned back in her seat, only to have Lanie poke her in the side. "Girl, why the hell are we even sneaking around? And why do _I_ have to pay for the cab?"

" _You_ got us into this mess!"

"No I didn't. I found you an amazing place to stay. You're the one _choosing_ to hide this from Castle. He's going to find out sooner or later."

Kate groaned, shutting her eyes. "Yeah, well I'd rather he find out later. I just want a few days of peace and quiet, is that too much to ask?"

Lanie reached for her purse to pull out a few bills for their taxi, telling her friend, "When you finally realize what a mess you've gotten yourself into, I'll be there, telling you I told you so."

* * *

Kate moved in without incident, imploring Eduardo the doorman not to tell Castle she's occupying the vacant unit on the third floor. After creating a white lie about planning an elaborate surprise for the Castle family, Eduardo agreed to keep her secret and pass the word on to the other doormen on different shifts. Kate thanked him profusely, making her way back up.

Her mind was still on maintaining the lie, so she was caught off guard when she heard a teenage boy speaking to her as she unlocked her door. Turning around, she saw that he looked like he's about to graduate from high school or enter college. That explained the chattiness.

"Hello, are you the new tenant? My name is Mike, I guess we're going to be neighbors. My parents have been wondering when you'd move in," he said, gesturing to his door across the hallway. "What's your name?"

Her brain, in its panicked state, told her, _LIE!_

"Ka-tya. Katya," she answered.

"Hey, you look kinda familiar. Have I seen you somewhere before?" Mike continued, still friendly as ever.

Her next terrible decision was to continue the conversation with Katya's persona. Putting on a thick Russian accent, she answered coldly, "No. And my boyfriend will not be happy knowing you ask many questions."

Mike took half a step back, as though he expected a member of the Russian Bratva to turn up at any moment. "Does he live here too? We uhh, haven't seen him around."

"No. I live alone. Good day to you, Mike."

With that, Kate entered her apartment, shutting the door behind tightly. Why did she have to dig herself into a deeper hole? One lie was bad enough, now she had Katya to deal with as well.

Kate leaned her forehead against the door and heaved a deep sigh.

* * *

It didn't take long for Castle to hear about his new neighbor. He gleefully shared his news with her as soon as he showed up at the precinct the next day. "Guess what, Beckett, the vacant unit beneath mine is now occupied!"

Kate tried to keep her voice nonchalant. "Oh?" She had been thinking it over all night, and decided to heed Lanie's advice. It was a silly lie anyway. However, before she had the chance to come clean, Castle ploughed on.

"Apparently she's _super_ hot and has ties to the _Bratva,_ " he whispered, waggling his eyebrows at her.

That stopped her short. Kate couldn't help but shoot back. "Have you even _seen_ her?"

"Well, no… but how cool is that? Can you imagine? A member of the Bratva, living in _my_ building! I'm sure management will hear about it soon enough, surely they won't let someone dangerous lease- hey, do you think she'll let me interview her for my books?"

"Castle, you'll leave her and the Bratva alone if you know what's good for you. I mean it. I'm not saving your ass from another Russian." Kate stood abruptly and walked away, leaving Castle alone at her desk. She paused at a corner, glancing over her shoulder and saw her partner looking a little lost.

Inside she was thinking, _Just what have I gotten myself into?_

* * *

The inevitable happened two days later. Castle finally bumped into Kate at the bodega down their street. She had been paying for her things at the register when Castle walked in.

"Beckett? What are you doing here?" he asked, genuinely surprised by her presence.

"Castle? I- What are _you_ doing here?" she turned the tables on him instead.

Pointing behind the counter, he said, "Best cold cut on the street. What's your excuse?"

Darn, she had even walked to the _further_ bodega in the hopes of avoiding a run in with Castle. "Well, I was… in the neighborhood. Visiting a friend."

Castle narrowed his eyes in suspicion. "What friend?"

"My friend, Claire." Kate averted her eyes, pocketing her change and hastily grabbed her things.

Castle grinned cockily at her weak lie. Before he could ask a follow up question, Kate made her way past him for the door. "Well, I gotta go now."

"Alright, see you around, Beckett."

She gritted her teeth, avoiding the bait of his teasing tone. Hurrying home, all she could think was, _that was close!_


	3. Chapter 3

A/N: This wouldn't be here without my beta extraordinaire, Katherine. Enjoy!

* * *

Castle exited the subway, holding the bouquet of flowers tight in his hand. He strode towards the loft, focused on getting home in one piece. The Mayan curse had been plaguing him and Castle wasn't about to take any more chances.

It started out small – a paper cut, innocent enough, but then his chair fell to pieces, the coffee machine exploded in his face, his pants got ripped by a dog, and he honestly believed he was about to plunge to his death in the precinct elevator.

As they wrapped up the case, Beckett convinced Cacaw Te to give up the remedy to Castle's situation. Cacaw obliged, whispering it into his ear, and Castle was surprised by the simplicity of it all. Bidding farewell to the team at the Twelfth, Castle hurried off to break the Mayan curse before his time ran out.

Castle entered his building, nodding in greeting to Frank. The crinkling sound coming from the paper-wrapped flowers reminded him of his task at hand. Loosening his grip around the precious cargo slightly, Castle strode to the side of the lobby, forgoing the elevator for stairs.

He wasn't going to test his luck until _after_ he broke the curse.

Instead of walking up to his loft on the fourth floor, Castle exited one floor below, crossing his fingers and hoping the person he was searching for would be home.

He knocked three sharp raps on the door and waited.

"Mike! Just the guy I was looking for," Castle greeted his neighbor with enthusiasm. Cacaw had specified that Castle would need the help of a young male, aged between sixteen and twenty, to help him break the curse. Castle's young, friendly neighbor should do just fine.

"Hey Mr. Castle, what can I help you with?"

"Mind helping me break a Mayan curse?" Castle held up the bouquet of flowers and waggled his eyebrows at Mike.

The teen's eyes widened as he grinned in excitement. "Cool."

* * *

Mike invited Castle in, explaining that his parents were out for the evening, entertaining old friends who had come for a visit. "So how'd you get cursed anyway, Mr. Castle? Does it have anything to do with your new book or was it from working with the police?"

"A bit of both, actually. We caught a case two days ago, and there was a Mayan mummy involved. Can you pass me a pair of scissors and a bowl? I'll tell you all about the case if you're interested."

Castle followed Mike into the kitchen, carefully cutting all seven flowers into the bowl as he painted a vivid picture for Mike, who hung on to Castle's every word. Being both a storyteller and performer with an inclination for drama, Castle played up his story, exaggerating the effects of the curse slightly. It made the story better and the stakes higher, both of which, kept Mike interested.

"So what do I need to do to break the curse?" Mike asked.

Castle brought the bowl of flowers to the sink and started filling it with water. "There are seven flowers, and you'll need to use each one to sprinkle water onto my head, chest, back, arms, and legs," Castle explained, turning off the tap when the flowers began to bob in the water.

"That's it?" Mike asked, sounding disappointed.

Castle shrugged. "Yeah, sorry man. The Mayans came up with it. It seems they channeled all their creativities into their curses. The cures are very simplistic in comparison."

"Alright then, so seven flowers, sprinkle of water, and the curse is broken?" Mike took the bowl as Castle nodded, repeating the places where Mike needed to sprinkle with water.

Mike grabbed the first flower, a yellow carnation, and pushed it into the water a few times to soak it. He then picked it up, gave Castle a warning, and began to flick water droplets on Castle's face.

Despite the warning, Castle still flinched when the first drops of icy water hit his face. He shouldn't have filled the bowl with cold water, but it was too late now.

"Sorry, but do I need to cover just your face, or the whole head?" Mike asked earnestly.

Cacaw didn't mention anything specifically to him, so Castle told Mike, "Might as well do the whole head, play it safe."

He turned so Mike could get to the back of his head, and then bowed down to get his crown covered.

The yellow carnation joined the rest of the discarded stems, and Mike picked up the second flower to repeat the process on Castle's chest. They worked through the flowers quickly, methodically _cleansing_ Castle of the curse. By the end of it, Castle was significantly damp and shivering occasionally while Mike strived to keep his laughter at bay. "I'll get you a towel to dry off a bit, Mr. Castle."

"Thanks for your help Mike," Castle said, gathering the discarded flowers and stems, rolling them in the paper wrapper it came in. Castle used the towel to dry off where he could, but he really needed to get home and change out of his damp clothes.

They both heard the soft chime of the elevator, and Mike told him, "That'd be Katya. Have you met her?"

"Really? No, I haven't, but I probably shouldn't meet her in damp clothes. First impressions and all that." What a let down. Castle really wanted to meet the new tenant in their building.

"You can still… I mean, you don't have to meet her, but if you're quick you can probably catch a glimpse through the peephole?" Mike suggested, tilting his head towards the front door.

Castle grinned at the teen, rushing over to the front door, damn near breaking his nose and taking his eye out in his haste to get to the peephole. Who he saw next was the last thing he'd ever expected.

Katya, the Russian beauty, turned out to be none other than Kate Beckett.

Castle waited until he heard her door open and shut before he turned back to face Mike.

"Well?" Mike asked expectantly.

Castle swallowed, his mind still stunned by this latest discovery. "I should- I should go. Thanks again, Mike."

Castle paused in the hallway, looking at her door. Katya's door. _Beckett's_ door.

A violent shiver reminded Castle of his damp clothes. He needed to get home and change or risk catching a cold. He headed for the opposite end of the corridor, looking back one last time, a million questions bouncing around in his head.

* * *

A/N: So how many of you guys thought the flowers were for Beckett? ;p Also, now that Castle knows, we're gonna have some fun!


	4. Chapter 4

A/N: Beta by Katherine. I really enjoyed writing this chapter, hope you guys like it too! x

Disclaimer: still not mine.

* * *

Kate had been fidgeting for the past fifteen minutes. She had opened her refrigerator, blankly staring at its contents before shutting the door with more force than was necessary. After that, she had picked up a book but could never seem to make it past the same two lines. Giving up, she had changed into workout clothes to attempt her yoga routine, but her mind kept wandering. Kicking her mat to one side, Kate returned to the kitchen for yet another staring contest with the inside of her fridge.

Her mind kept going back to the conversation she had overheard between Castle and Ellie Monroe. _Upset and in need of comforting_. Kate rolled her eyes. Is that what the cool kids were calling it nowadays?

Kate glanced at the clock sitting on her shelf. 7:08pm. She also knew that Castle had invited the actress over to his place for dinner at seven. He didn't exactly keep his voice down earlier.

Kate stared at her ceiling. Maybe if she stared hard enough she could develop X-ray vision- No. She absolutely did not want to accidentally catch them _in flagrante delicto_.

She couldn't help but wonder what was going on in the floor above. Did he even prepare dinner? She knew his cooking skills were good enough to charm and impress any date – after all, she had been a recipient for the duration that she had spent living in his guest room. Kate glared at the ceiling. Or did they just tear the clothes off of each other and get right down to business?

She picked up her book, enjoying the karmic justice of it being Patterson's newest thriller, and tried to read it once more. Alex Cross was getting married in this book but his plans were put on hold because… Kate honestly didn't even know what she had been reading.

This was ridiculous.

What kind of friend would she be if she allowed Ellie Monroe to just _use_ Castle? She should go over and warn him of the actress' sneaky ways. Because that's what a good friend would do.

Kate threw on a jacket and headed out before she could change her mind.

Fifty seconds later, she was knocking on his front door. She transferred her weight from foot to foot, unable to remain still with all her nervous energy.

The door opened and she had to stop her eyebrows from rising too far.

"Beckett?"

She took in his disheveled hair and swollen lips, the way his chest heaved with every breath, and just behind him, Ellie Monroe in a similar state, looking annoyed. At least they were still fully clothed.

Kate narrowed her eyes at him even though she had no right to do so. "Castle, I was just about to call you."

"Who's this, Rick?" Ellie asked, making her way over to the front door, leaning into his side. To his credit, Castle flushed and took a small step away from the actress.

"Ellie, this, uh… this is Detective Kate Beckett. We work together- well, I shadow her for my books."

"Nikki Heat? Oh, I imagined someone more… well," Ellie trailed her eyes up and down Kate's figure.

All of a sudden, Kate felt small and inadequate. She was still wearing her workout clothes from earlier while Ellie was dressed to impress. Or… _seduce._

"I guess I imagined someone different," Ellie finished at length, smiling a perfect smile that must have cost a pretty penny.

Kate threw a fake smile at the actress, turning to tell Castle, "I left something in the guest room. You know, from when I was staying here." She cringed as the lies just rolled off her tongue.

Kate caught the actress frowning at that and she had to resist the urge to smirk in triumph. Something about Ellie just made her feel catty.

"O-kay," Castle shuffled aside to let her in. As Kate rounded the stairs leading to the upper story of Castle's loft, she heard harsh whispering from below. She allowed herself a tiny smile and continued on.

* * *

By the time Kate returned downstairs, Castle was sitting by the kitchen island, alone.

"Found what you needed?" he asked, his tone biting.

Kate kept her face neutral. "Yes I did, actually. Where's Ellie?"

Castle threw her an incredulous look, effectively conveying his thoughts. He didn't buy her innocent act. "She _left_."

Kate joined him in the kitchen. "What, you're disappointed you didn't get to sleep with her? Oh come on Castle, you know she's only doing this to try and score a part in the Heat Wave movie, right?"

"And you just happened to drop by my place?"

"I was in the area," Kate defended.

"Yeah, you seem to be in the area pretty often despite having moved out of the loft. Why, Beckett, do you live somewhere nearby?" His tone turned playful, goading her as a small grin adorned his face.

Since when had the tables turned on her? But before Kate could make a decision to come clean about her lie or formulate yet _another_ lie, Castle continued in the same carefree way, "Or did you just miss me?"

She rolled her eyes at him. "I'm leaving now," she announced.

"Oh come on, don't leave. You've already chased off my-…" Castle stopped short as Kate arched her brows at him, daring him to finish that sentence, "Anyway, I have all this food and no dinner companion. So the least you could do is stay on for dinner."

She pretended to consider his offer as Castle headed for the stove. Walking past him to grab two wine glasses from his cabinet – she had gotten surprisingly familiar with his kitchen during her short stay at Casa Castle – Kate asked, "So, do you want red or white wine?"

* * *

Two days later, they closed the case and found out Ellie Monroe had been sleeping with Mr. Weisburg, the president of the network, the whole time. Castle showed up at her precinct desk in the evening, produced a packet of M&M's from his pocket, and mumbled his gratitude towards Kate for ruining his date with the actress.


	5. Chapter 5

A/N: Another fun one before tomorrow's final installment! Thank you so much Katherine for the beta ;)

Disclaimer: not mine

* * *

It'd been a week since Castle found out that Beckett moved into his building, but even after their one run in at the bodega a few days ago, he hadn't managed to catch her on the premises and confront her about the secret.

That all changed when he returned on Thursday evening and saw her paying for take out in the lobby. Frank, one of the senior doormen was giving the new guy a lecture - he probably didn't let the delivery guy through, which explained Beckett's presence in the lobby.

The detective hadn't noticed his presence in all the commotion, so Castle decided to have some fun with her. Nodding a silent greeting to Frank, he sidled up behind Beckett quietly.

"Hey Beckett!" He barked in her ear, delighting in the way she startled so bad her purse clattered to the marble floor.

She was still slow to react, so Castle bent down and picked up the purse for her.

"Ca- Castle, hey," she said, her tone pitched higher than usual. She took her purse from him, so flummoxed and at a loss for words that she couldn't maintain eye contact with him.

"Whatchu got there?" Castle asked when it became obvious no intelligible words were going to come out of her mouth despite it opening and closing a few times.

"Dinner. Take out," she elaborated unnecessarily. The contents of the box were obvious enough, the fragrant smell of curry wafting up into the air. "And..?" He prodded, unable to resist toying with her.

"It's... For you. I thought you could do with some cheering up," she said, lips quirking up weakly in reference to Ellie Monroe's line. Castle eyes the take out bag, knowing it isn't heavy enough to be anything other than _dinner for_ _one_. It was obvious to him that if it weren't for the mistake made by the new doorman, she'd be happily enjoying the curry in the comforts of her home already.

Castle stared at Beckett as he pondered what to do. It was obvious she still thought he was unaware that she's living below his loft, and he _could_ take the dinner she'd offered, but… she had that look in her eyes. There was guilt, sure, apprehension and false bravado, but underneath it all, he recognized something much more powerful and familiar.

 _Hunger_.

He's spent countless hours with her in the precinct, and he knows just how terrible her eating habits were. And when her blood sugar began to drop, her tells began to show. There was _Snarky Beckett_ , _Growly Beckett_ , and _Hangry Beckett_. Kate Beckett was hungry and Castle was almost tempted to poke the bear, or in this case, take the honey away from the hungry bear. That would show her to keep secrets from him.

A rumbling sound filled the air, its source unmistakable. Beckett flushed an adorable shade of pink, dropping her head again to avoid facing him. Castle took pity on her, giving her an out instead. "While I appreciate the gesture, why don't you come up with me? I have dinner heating on the stove, and we could share all the food instead."

She peered up at him, biting her lower lip. She was wearing flats, and the height difference made Castle's protective instinct come to the forefront. "Come on up, Beckett, I insist. I can't have a member of the NYPD fainting a block from my place, Captain Montgomery would have my head!" That ought to do it.

Beckett smiled up at him, rolling her eyes as she gestured for him to head for the elevators.

* * *

He let them into the loft, and Beckett headed straight for the kitchen, greeting Alexis warmly. His daughter set the ladle she'd been using aside, surprised by Beckett's unexpected presence. "Detective Beckett, I didn't know you were coming over for dinner."

"It was a last minute thing, pumpkin," Castle told her, dropping a kiss on her head in greeting. Beckett smiled at his daughter as she set the take out bag on the counter. She then opened the kitchen cabinets and began taking out plates and bowls. Castle's heart warmed at how comfortable she seemed to be in his home.

"I hope you don't mind, Alexis, but I ordered some curry. Sorry, it's not much."

Alexis picked up her ladle and resumed stirring the soup. "Oh no worries, I'm actually heading to Paige's place for dinner and movies. I'm just minding the food until dad returned. Hey, you guys can finish off your marathon of the X-Men movies! Paige told me that First Class will be coming out next year with an all new cast of young people. Here, we can set up dinner in the living room. I'll prepare the projector for you guys."

"Martha would be bored to tears," Kate protested, stalling his daughter.

"Don't worry, Grams is out and won't be back until-… well, tomorrow, maybe."

Alexis bustled out of the kitchen, leaving the two adults alone.

"If I didn't know better Castle, I'd say you've set your daughter up to arrange a dinner date for us," Beckett drawled, giving him a wry smile.

He shook his head at his daughter's meddlesome ways, telling his partner, "I swear that's all her. I have no idea where she gets it. Look, we don't have to watch the movie if you don't want."

"It's alright, I didn't have plans for my evening anyway."

Alexis returned to the kitchen just as Castle finished plating their dinner. "Here, Dad, let me help you with that." She carried some of the food to the living room, ushering the adults to sit down.

"Enjoy your dinner and movie, I'm off to Paige's!" Alexis winked at Castle while Beckett's back was turned. She was in the middle of mouthing, "Good Luck," when Beckett turned around and caught the teen in the act.

Alexis blushed bright red, ducking her head so that her hair fell forward to obscure her face as she scuttled out of the loft.

"I, uhh... Well, Alexis was- she just, uhh..." Castle stammered. Even _he_ couldn't find the words to explain his daughter's behavior.

"She's rather... Heavy handed," Beckett commented. There was an underlying teasing tone to her voice, so Castle chanced a glance at her face. She caught his eye and grinned. That was all it took to make Castle deflate, exhaling a breath he hadn't even realize he was holding. With the tension now broken, they shared soft laughs and began tucking into dinner.

* * *

The movie had ended a while ago, and an empty bottle of wine now sat between Castle and Beckett. The conversations continued to flow easily between the partners, transitioning from topics ranging from work to music preferences. Castle checked his cellphone for the time when Beckett excused herself to use the washroom, and he was surprised to find how late it was already. If this had been a date - which it _wasn't -_ he'd have declared it a very successful one. He normally had to put in more effort in order to make his dates comfortable enough to have conversations the way he and Beckett did.

Castle hummed a happy tune to himself and cleared their empty glasses, loading them into the dishwasher.

"Hey Castle, I should head back. Thanks for the dinner."

Castle straightened, working to keep the disappointment off his face. He knew she'd have to leave eventually, he just didn't realize eventually would be so _soon_.

"Well it's late, why don't you crash in the guest room?" He offered. Logically he knew she lived downstairs, and going home wouldn't take more than ninety seconds. But a small part of him wanted to take advantage of Beckett thinking he's still unaware of her new residence.

"It's fine, it doesn't take…"

The almost-slip hung in the air between them. They stared at each other in a stalemate, Castle using his eyes to practically dare her to come clean. Beckett's pupils dilated with the adrenalin coursing through her bloodstream, and at long last, she blinked and caved first.

"I'll just head home, Castle. Good night."

Castle forced a smile. He couldn't help but feel disappointed in her for holding on to her silly little secret.

"Until tomorrow, Detective."


	6. Chapter 6

A/N: As always, my gratitude goes to Katherine for her patient guidance and for making this story a thousand times better. Xx

Disclaimer: never gonna be mine.

* * *

Tom Demming spelled trouble. There was just something about the handsome robbery detective that didn't sit well with Castle. It wasn't just his too-good timing or the coy looks Beckett kept shooting towards the newcomer. He was sniffing around Beckett and frankly the dynamics of their four-person team was just _off._

Which was why Castle's mind, when Demming asked him if there was anything between him and Beckett, went completely blank and he blurted out, "No." Because how do you explain such an intricate relationship to a complete outsider? It didn't just boil down to a simple yes or no.

Unfortunately, Demming wasted no time moving in on Beckett, inviting her to watch the bank footage with him in the morning. She agreed to it, a tad too quickly for Castle's liking, leaving him with a bitter taste in his mouth.

There was only so much sulking a grown man could do, so Castle left the precinct to clear is head and sort out his emotions.

Things had been going well with Beckett. He'd had to slowly win back her trust and friendship after she allowed him to return to the precinct, but their dynamics had improved. For months they were… happy.

The past month had allowed Castle to see a different side of Beckett. She had only stayed at the loft for a few days after her apartment blew up, but in that time, Castle was gifted a glimpse into her life away from the precinct. She enjoyed cooking but wasn't very good with cleaning up, preferred movies to TV, enjoyed singing in the shower, and she really was an absolute grouch before her morning coffee. Even Martha and Alexis learned to stay clear of her until she'd had at least half a cup of coffee.

Castle had been interested in Beckett from the start but she had always brushed him off, so Castle assumed she just wasn't interested. But _then_ she crashed his date with Ellie Monroe last week, and Castle had begun to wonder if maybe she _did_ feel something after all.

But then Demming had to come and mess things up.

Castle eased the door to the loft open slowly, pausing at the entrance, the heavy weight in his gut making him feel lead-footed too. He shuffled inside, hoping for a quiet evening in, but Martha and Alexis roped him into a game of poker. Teaching Alexis the intricacies of the game took his mind off Beckett, chasing away the melancholy for a short while.

Alexis was a fast learner and attentive student, and soon they began to bet on chores and favors. They called an end to the game of poker after a particularly spectacular defeat on Castle's part. As Alexis gloated and counted her winnings, Castle lamented, "I'm not used to losing."

Alexis stopped celebrating to tell him smartly, "Then do something about it."

Castle froze as a light bulb went off in his head. Alexis was right, he _should_ do something about it. Shoving his chair back as he stood, Castle yanked off his green poker visor. "Could you put away the poker things? I need to-"

"Go see Detective Beckett?" Alexis cut in, giving her father a knowing smile. Castle started to talk but she waved him off, saying, "It's okay, you've been distracted all evening, I could tell. Go sort things out with Detective Beckett."

Castle brushed a parting kiss on the top of his daughter's head and went downstairs to confront his partner.

* * *

Castle knocked on her front door impatiently, only stopping when he heard footsteps approaching. When the door didn't open, Castle put his eye to the peephole and called out, "Open up Kate, I know you live here."

The door flung open to reveal a flustered detective. "What- how long-"

"Oh please, Kate, your presence in this building is the worst kept secret in Manhattan." He pushed past her to stand in the vestibule as he gestured his way through a list, "The doormen think you're having an identity crisis; half the tenants are _mildly_ amused at your antics whereas the other half are completely indifferent." Castle flung an arm out to gesture through the door as he continued, "Mike, poor kid, is the only one who even believes you're remotely Russian at this point. I played along just to see how long you'd keep up this charade, but last week you dropped by my place unannounced-"

Kate raised her voice to cut him off as she slammed the door shut, "I saw the way you kept sneaking looks at Demming today. So what, this is payback for crashing your date with Ellie?" Kate's face was flushed a deep shade of red by the time she'd finished interrupting him.

"No- Yes, actually. You helped me dodge a bullet last week and I'm just returning the favor," Castle defended, shoving his hands on his hips and pursing his lips. Why did she have to make it sound like he was being petty?

Beckett crossed her arms and sniped, "Tom is nothing like Ellie."

It's _Tom_ now. Castle had to resist from rolling his eyes at her. "Ellie wasn't the right person for me, and neither is _Tom_."

"I didn't realize Tom was interested in you," Kate smirked. "Don't worry, I'll pass on the message."

Castle growled at her in frustration. He stepped closer and towered over her. "Why are you being so childish?"

"Why are you butting into my business?" Kate stood her ground, coming toe to toe with him and poking him in the chest with a pointed finger.

"Because Tom isn't the right guy for you!"

"And _you_ are?"

Her question stunned them into silence, their shallow breathing the only sound in the air. Castle felt the blood rushing to his brain as he saw her eyes widen. His pulse thrummed in his ears when he watched her gaze flit to his lips before returning to his eyes.

Castle broke the silence with a soft but determined, "Yes," and sealed his lips over hers. She leaned into him instantly, her hands snaking up his chest to loop at his neck, and he pulled her closer to him, erasing any space left with a strong arm tight around her waist. When they eventually broke apart, he felt her lashes brush his cheek, and as they gazed into each other's eyes, he wondered if this was what all those clichés about 'coming home' felt like.

* * *

The next morning, Kate went to the precinct to review the security footage with Demming. He began to offer her a cup of coffee, but Beckett pulled out her travel cup, telling him, "Thanks, but Castle's got me covered."

Fin.

* * *

A/N: Thank you so much Lou for the prompt, I hope you really like your extended birthday present ;) That's it guys! Thank you so much for reading my story, and for all the reviews, follows and favourites. Also, let me know if you guys would be interested in a follow up story.


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